Peacemaker and divisive former IRA spokesperson says he will retire next year after leading Sinn Fein for 35 years.

Gerry Adams, the veteran leader of the Irish Republican party, Sinn Fein, has announced plans to step down from his role after almost 35 years.

His replacement will be elected by party members in the coming months, Adams told the party's annual conference in Dublin on Saturday.

"Leadership means knowing when it is time for change and that time is now," Adams said in his speech.

The Belfast-born 69-year-old leader has long been a divisive figure in Ireland and the United Kingdom.

He was a leading spokesman for Sinn Fein's paramilitary wing, the Irish Republican Army (IRA), during its decades-long bombing campaign aimed at ending British control of Northern Ireland.

Adams was also a key figure in peace negotiations in the 1990s, which saw Sinn Fein enter a government with their pro-British counterparts.

The Belfast Agreement - dubbed the Good Friday accord - largely saw the end of violence in Ireland in which more than 3,500 people lost their lives.

The 1998 deal fell short of the IRA's goal of a united Ireland, but the movement largely remained united behind the leadership of Martin McGuinness and his long-time colleague, Adams.

"I thought I needed to tell you … I have been privileged to be part of an amazing leadership," Adams said in his speech to the Sinn Fein conference.

"One of our greatest achievements has been to build a peace process. I will not be standing for the Dail," he said, referring to the Irish parliament.

'Somewhat toxic'

Ken Murray, a correspondent for Politico in Dublin, said Adams' replacement would likely be untainted by links to the IRA.

"The established parties Fine Gael and Fianna Fail don't want to do business with Sinn Fein because, with Adams in charge, the party is viewed as somewhat toxic," Murray said.

"Fine Gael, who are the governing party here, and the main opposition party, Fianna Fail, believe that as long as Adams remains in charge of Sinn Fein it is viewed as being a terrorist party," he added.

Murray argued that with Adams stepping down, Sinn Fein will find it easier to develop relationships with other Irish parties, giving it the potential to be part of future coalition governments.

"Adams has been in charge of Sinn Fein since 1983. But things have been happening here over the last couple of years. In the general elections last year in the Republic of Ireland, Sein Fein increased its number of seats in the Dublin parliament from 14 to 23," Murray said.

"They all but wiped out the Irish Labour Party and they ended up holding the balance of power," he added.

Adams said the move to leave politics to the next generations was agreed upon with McGuinness before his death in March. Michelle O'Neill, 40, was elected as Sinn Fein's leader at Stormont (Northern Ireland parliament).

Party delegates elected Adams to carry on as president until 2018 and agreed to hold a special conference to discuss the new leadership.